It is possible to generate water by the use of fuel cells or other suitable processes. Water produced in such cells or processes must meet several regulations depending on the intended type of use, for example water intended for flushing toilets does not need to meet requirements for potable water or shower water. Wash water and air humidifying water in air conditioning systems must meet still other requirements. For example, potable water must be suitable for drinking by humans and must meet the regulation requirements of national and international potable water regulations. Shower water and wash water used in aircraft must also meet potable water qualities in accordance with national and/or international potable water regulations because shower and wash water may also enter the human body. Water for humidifying the air treated by an air conditioning system must be free of germs, free of fungi, and as free as possible of salts in order to avoid deposits in the air conditioning and air distribution system. Similarly, water that is intended for flushing toilets should also be free of germs and free of salts in order to avoid deposits in the equipment where such water is used.